Well Pumps and A/C Units Concerns

[CoyotesDenHomestead]

Hi guys, we are living in two fifth wheel trailers on our property (2 Parcels at 3.2 acres each) for the next year or so waiting for houses to get built, already been here 8 months.
Right now we have 3 gas generators, one on moms trailer, one on mine and one for the well, burned up several generators already through the hot AZ summer.
I am trying to decide which solar to go with, I have my eye on the MPP LV6548 but have concerns about my well pumps and a/c units on it.
I plan on using this system on the new house if it ever gets built as well. Solar Equipment will be housed in a shipping container for now.
My loads:
2 x 50amp Trailers - Each has two a/c units running hard during the day and some at night.
1 x 3HP Submersible Well Pump 600' Deep - Runs once a week for several hours - Could keep this on generator.
1 x 2HP Pressure Pump - Runs for a min or two several times a day.
1 x Full Size Refrigerator
1 x Washing Machine, we line dry.
1 x Starlink Internet 24/7 - Right now I have it on an 100ah LifePo4 Battery connected to a Lithium RV Charger on one of the generators.
1 x (future)Mini Split a/c & heat for the Shipping Container to maintain safe temps for equipment.
What do you think would be best and any tips?
I rather build this right the first time.

 

[MichaelK]

Forget about the MPP LV6548 running either of your well-pumps. What pumps need is substantial startup current, and a high-frequency transformerless AiO will not provide that.

I'm running a 1hp well-pump, and the startup surge is about 9200W. Even your 2hp will be substantially higher. Get a clamp meter on those pumps and measure their inrush, starting currents. You need to be working with real numbers instead of just guesses. Take a look at the Schneider XW6848, and the Outback Radian 8000. For your pumps most likely you may need two units in parallel to handle the starting surge. I have the XW6848, and it starts my 1hp pump without blinking.

Measure the running watts, and plan on installing 2X the watts of panels as what your loads would draw. Until you get some hard numbers, start planning on at least 6000W of panels.

 

[pvdude]

Get one of these to measure the instant LRA (Locked Rotor Amps) of anything w/ a motor in it.

CM1000A 1000A T-RMS AC/DC Clamp Meter

Amazing deals on this 1000A T-Rms Ac/Dc Clamp Meter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

For example, our 1hp well pump need 41A to start. Running current is about 8A.
We have a single Schneider XW Pro 6848 inverter running the well pump and an wall AC unit, plus a small refrigerator and some LED lights.

XW Pro 120/240V

The Schneider Electric XW Pro 6848 solar inverter provides flexible design with optional generator integration for home and small businesses.

solar.schneider-electric.com

The inverter will provide 6800 watts continuous, 8500 watts for 30 minutes, 12000 watts for one minute.

It starts the well pump and wall AC units easily.

However, the inverter will not start the heat pump, which I measured as 132A LRA.
To start the heat pump, I would have to add two more 6848 inverters, all connected together to form a multi-unit power system.
OR
Add a Hyper Engineering soft start to the heat pump, and then it would start with the single inverter we have now.

Eltwin Hyper | Eltwin

hypereng.com

 

[MichaelK]

Here is pump data that I copy and pasted from another solar enthusiast, Mike92450. Although I still think it prudent to measure the starting amperages of your own pumps, it gives you a place to start. Focus your attention on the collumn labeled "start". Looking at the 2hp pump, I see a starting surge of 57A, and 77A for the 3hp pump. The 37A value for the 1hp closely mirrors what I myself have measured.

Expect a similar startup demand from your refrigerator and air-conditioners, somewhere in the 3-4X range. But, with the clamp you can measure it, instead of just guessing.

 

[CoyotesDenHomestead]

Thanks guys, I did plan on gathering real numbers, just needed that nudge in the right direction of equipment. This helps a lot.

 

[MichaelK]

Getting back to your choice of the MPP LV6548, since you have to wire two together to get split-phase 120/240VAC, two units MIGHT be able to start your 2hp pump. Not having any experience running something that big, I can't say with any certainty. I'd be looking at batteries in the 600Ah range. This is what I've got.

4 CS 17P | Rolls Battery

www.rollsbattery.com

 

[pvdude]

^^^
WOW, serious batteries....

 

[Tecnodave]

There is a huge difference between a low frequency inverter with a wound iron core transformer and a high frequency toroid core inverter which has a ”air core” The iron core inverter can and does recycle the power reflected by the hugely inductive loads of a wound core deep well pump through its iron core....

I have a very antique DynaMote Brutus Inverter which is only 3200 watts 120 volts which has a far greater surge capability than any 5,000 watt 240 volt inverter....the Brutus inverter has a whopping 11,900 sustained surge capability vs a 9800 watt 60 second surge capability of the typical toroid core inverter

In a side by side comparison of a MagnaSine MS4024AE 4,000 watt 5800 watt surge 120/240 volt inverter and the stone Antique Brutus 3200 watt 11,900 watt sustained surge 120 volt inverter driving a Trace autotransformer to get the required 240 volts to drive the pump

The MagnaSine will grunt starting the deep well pump sometimes tripping the breaker , but runs it just fine
The Brutus starts it easily without a complaint and runs it without a compliant

What is the difference......The Brutus iron core transformer is huge compared to the MagnaSine iron core transformer
The huge iron core can and does “recycle” the reflected power of the hugely inductive load of the deep well pump and corrects the lag of current vs. voltage of such a hugely inductive load

The Brutus is long gone, Its days were before the legendary Trace of days past..

its got its bad points.....it idles at 4 amps.....96 watts.....huge compared to modern inverters
but this was the first high/low frequency inverter design.....
all the modern high/low frequency inverters are an evolution of thr Mighty Dynamote Brutus......

that includes the MagnaSine........Outback.....Schneider......Samlex EVO...

I still have 2 Dynamote Brutus Inverters in use.......for those difficult loads, in the winter when water levels are higher I can get away with using my MagnaSine to drive the deep well but late in season when my water table drops below -350 feet, time to reconnect the Brutus.....water is more needed than the extra power that the old hardware uses.

Bottom line......Use an iron core inverter for deep well use

Highly recommended are the bigger Schneider , Outback, and MagnaSine units.....Samlex EVO....which are all iron core ...especially if you need to pump from -300 to -400 feet.....common in the western US

Not recommended are the Chinese toroid core inverters especially the all-in-ones that are inverter/charger/controller

 

[pvdude]

That explains why the Schneider inverter we have weighs 120lbs......

 

[Tecnodave]

Yes, absolutely....The Schneider XW 6648 is a very awesome unit and highly recommended for driving a deep well pump

If it’s an asian unit weighing 18 pounds.....lots of luck doing that

 

[pvdude]

Yep! And there are aerobic benefits too, no need to lift weights....

 

[Tecnodave]

I love it....All Schneider....and Rolls Surette...way to go. This should give you good service for many a year

My system is of comparable quality and build but just different manufacturers....MidNite, MagnaSine and Rolls Surettes

 

[MichaelK]

Yep! And there are aerobic benefits too, no need to lift weights....View attachment 65366

Can we see a pic of your other toys, the ones clipped off on the far right?

 

[pvdude]

OK, but it is a disturbing amount of stuff......

 

[MichaelK]

OhhhhKkkkkk, that's impressive!!! I don't even know what it all is?

 

[Tecnodave]

Ahhhh, a radio junkie......I do recognize some of it but not all for sure, amateur radio operator for sure

 

[hicktown21]

A lot of great information here... Would anyone want to comment on my situation or is it in the same realm of the first question..??

Trying to be as cost conscious as I can and I have been speaking to off-grid solar companies and it seems all of them want me to build a huge production plant. I am a complete novice at all the lingo but getting better by watching videos, reading and viewing comments here in this forum.

Based on the info below and the pump tech information can anyone point me in the right direction. I am ready to purchase and install once I have all the components. I will be going with a lithium battery set-up for possible emergencies.

The well pump is my biggest energy (start-up from reading here) pull and I will only use it during the long AZ sun days. I don't see running the well pump at night unless an emergency or I messed up the scheduling. The water is being pumped up to very large holding tanks and the pump is only rated at 7gpm (see pump tech worksheet)

Listed the items below and usage expected.

** 2HP well pump (7gpm) - see attachment for specifications (the pump will only be used during daylight hours, run 2x a month and runs usually for 5 hours) no other appliances will be ran during this time.
** Clothes washer (runs a few times a month when in use)
** String lights to be used only during the night will LED.
** One ceiling fan (not on all the time)
** ½ hp RV pump to run water to 3 shower locations (runs a few times a month when in use)
** A few cell phone charging stations/plug ins

Thank you all..!!

 

[MichaelK]

I took a look at the attachment, and I'd say no way can the numbers they wrote down be accurate. They listed 10.2A on L1 and 11.67A on L2? Immediately, that makes me very suspicious that they were NOT using a meter that can read inrush. Again, referring to the chart posted above, I find the numbers in this chart to be an accurate representation of what you will actually see.

Looking at the chart, I see 13.2A running, with 57A starting. At 230V that 57A means 13,100W for maybe 500 or so milliseconds. That is a really massive starting surge and I don't think there is a single inverter that will power that alone. But, either two XWPro 6848s or two Radian 8048s wired in parallel should be able to handle that surge. You are talking though about 7600-8800$ just for two inverters, depending on which you chose. Maybe a single Sol-Ark SA-15 might handle it.


If you go that route, I'd suggest using the 2X rule for solar panels, that is have double the watts of panels for your biggest single load. That is.....
13.2A X 230V X 2X = 6072W of panels. Call it 24-27 250W grid-tie panels.

Yes, it's doable, but the cost is going to be very high. I don't think one other load you might have is going to approach what that pump needs. Since you only plan to run the pump a few times/month, one alternative is the design a system around everything else you need to power, and use just a generator biweekly to power the pump.

The amp level coming out of the battery suggests you'll need a 48V battery in the 500-600Ah range to meet that need.

So, nothing about this is going to be cheap!!!

 

[hicktown21]

I took a look at the attachment, and I'd say no way can the numbers they wrote down be accurate. They listed 10.2A on L1 and 11.67A on L2? Immediately, that makes me very suspicious that they were NOT using a meter that can read inrush. Again, referring to the chart posted above, I find the numbers in this chart to be an accurate representation of what you will actually see.

Looking at the chart, I see 13.2A running, with 57A starting. At 230V that 57A means 13,100W for maybe 500 or so milliseconds. That is a really massive starting surge and I don't think there is a single inverter that will power that alone. But, either two XWPro 6848s or two Radian 8048s wired in parallel should be able to handle that surge. You are talking though about 7600-8800$ just for two inverters, depending on which you chose. Maybe a single Sol-Ark SA-15 might handle it.
View attachment 111349

If you go that route, I'd suggest using the 2X rule for solar panels, that is have double the watts of panels for your biggest single load. That is.....
13.2A X 230V X 2X = 6072W of panels. Call it 24-27 250W grid-tie panels.

Yes, it's doable, but the cost is going to be very high. I don't think one other load you might have is going to approach what that pump needs. Since you only plan to run the pump a few times/month, one alternative is the design a system around everything else you need to power, and use just a generator biweekly to power the pump.

The amp level coming out of the battery suggests you'll need a 48V battery in the 500-600Ah range to meet that need.

So, nothing about this is going to be cheap!!!

Wow... Thank you for the great explanation. Simple has turned to back to the drawing board for redesign... I have a generator that handles the well pump and it looks like that will be the case for the next year until I decide how to move this forward. Again, thank you for taking the time to respond..!!

 

[OzSolar]

Yes, it's doable, but the cost is going to be very high. I don't think one other load you might have is going to approach what that pump needs. Since you only plan to run the pump a few times/month, one alternative is the design a system around everything else you need to power, and use just a generator biweekly to power the pump.

Yep. I've done a bunch of off grid systems over the years. The designs for the ones that had well pumps was totally dominated by the well pump. Every other load was inconsequential when it was all said and done.